From what I can tell, it's all set pieces on a straight line.
You could add some platforms, enemies, or walls.
The ground pattern is still somewhat repetitive, but it looks much better than where it was originally.

I have a question, what happened to the ring frames did you try to add new frames/art because its colliding with the HUDs VRAM spaces now? The rings VRAM spaces are next to the HUDs if you didnt know, and if you dont know how to look at the VRAM use Exodus or Bizhawks VRAM viewer its very helpful for things like this.

I figured, I was just wondering how it happened, I pretty much answered my own question though. Also the layout seems okay but there were a couple times the flow seemed to be off, since I saw you get stopped abruptly in some areas. Not much to say about the art though since so far only the bushes have been added but some of those custom chunks looked a little odd. Like the chunk that usually had all those rings layed out in the shape of a “2”. Also did I see an arrow made with rings because some people have a problem with that and I can see why especially since there is a ring limit, also its a little pointless.

So after 3 god damn months, I finally got Tails' tails working in Sonic 1. I had a lot of help from Team Kyukyoku members and others. But let's have a comparison of the progress in that time;
September 11, 2018

December 30, 2018

You'll notice that the Spindash is a little bugged out, but it was fixed afterwards.

AsuharaMoon; that is a pretty nice teaser, not over the top, and I love the cinematic style. I would love for this to actually be in-game itself as a sorta intro video before the title, but I assume it's not and is just for the video.

maple_t; not a bad night palette, it looks as though there's a full moon brightening everything up, I notice the BG is different too to reflect the night. Could I recommend adding perhaps some stars? They don't have to be large and obnoxious mind, but some small and relatively faded ones using the horizon colours would probably be enough.

maple_t; not a bad night palette, it looks as though there's a full moon brightening everything up, I notice the BG is different too to reflect the night. Could I recommend adding perhaps some stars? They don't have to be large and obnoxious mind, but some small and relatively faded ones using the horizon colours would probably be enough.

I remember the boss from the original was a bit more interesting when it comes to patterns and the tail movement, and it definitely did not have that issue where the boss flips, and the whole tail part just teleports to the other side. Otherwise it's gonna be fun to see where this could go!

It looks like a sun to me, not to say a moon cannot be yellow as I also believe a moon being yellow at that position in the horizon is common, but it still looks like a sun to me. Perhaps use a more white-ish colour even if it's just a tint yellow?

Another aspect is the night skies brightness. I believe it would be brighter with the moon in that position, if it's not the moon itself brightening up the atmosphere, then it'll certainly be the sun which should in theory still be on the horizon behind you to make that moon full.

Of course, I don't want to encourage you to ruin your background further by making changes, I thought the backgrounds' brightness was fine and didn't clash with the FG, likewise, I'm not saying you should remove the moon either. Your image doesn't look horrible, it looks nice, it just doesn't seem logical, but I wouldn't say its wrong either, so I don't want to encourage you to make changes to your hard work, I am merely pointing out a tiny nit-pick, that's all, so feel free to ignore me if you wish, at any rate, well done so far~ =)